Since all NodeInputs will generally only need their data type and default
value set once, we place it all into the constructor for cleaner and easier
to manage code.
It seems unwise to let NodeInputs take more than one value, but at times
it makes sense to create a list or array of inputs. This class will create
sub-parameters as an easy way to provide variable inputs while also enforcing
one connection per input parameter.
This is also the primary motivation for the previous commit (disambiguating
when a NodeParam's parent is a Node vs some other type).
Old code assumes that a NodeParam's parent will always be a Node. The function
has been separated off and tweaked in the event that this is not the case.
itsmattkc